1. Field of the Invention
The invention relates to aluminum based alloys having strength, ductility, toughness at ambient and elevated temperatures and relates to powder products Produced from such alloys. More particularly, the invention relates to Al-Fe-Si-X alloys that have been rapidly solidified from the melt and thermomechanically processed into structural components having a combination of high strength, ductility, fracture toughness.
2. Brief Description of the Prior Art
Methods of obtaining improved tensile strength in aluminum based alloys have been described in U.S. Pat. No. 2,963,780 to Lyle et al.; U.S. Pat. No. 2,967,351 to Roberts, et al.; and U.S. Pat. No. 3,462,248 to Roberts, et al. The alloys taught by Lyle, et al. and by Roberts, et al. were produced by atomizing liquid metals into finely divided droplets by high velocity gas streams. The droplets were cooled by convective cooling at a rate of approximately 10.sup.4 .degree. Cs.sup.-1. As a result of this rapid cooling, Lyle, et al. and Roberts, et al. were able to produce alloys containing substantially higher quantities of transition elements than has hither to been possible.
Higher cooling rates using conductive cooling, such as splat quenching and melt spinning, have been employed to produce cooling rates of about 10.sup.5 to 10.sup.6 .degree.0 C.s.sup.-1. Such cooling rates minimize the formation of large intermetallic precipitates, with accicular or blocky morphology, during the solidification of the molten aluminum alloy. Such intermetallic precipitates are responsible for premature tensile instability.
U.S. Pat. No. 4,379,719 to Hilderman, et al. discusses rapidly quenched aluminum alloy powder containing 4 to 12wt % iron and 1 to 7wt % cerium or other rare earth metals from the lanthanum series.
U.S. Pat. No. 4,647,321 to Adam discusses rapidly quenched aluminum alloy powder containing 5 to 15wt % iron and 1 to 5wt % of other transition elements.
U.S. Pat. No. 4,347,076 to Ray, et al. discusses high strength aluminum alloys for use at temperatures of about 350.degree. C. that have been produced by rapid solidification techniques. These alloys, however, have low engineering ductility and fracture toughness at room temperature which precludes their employment in structural applications where a minimum tensile elongation of about 3% is required.
U.S. Pat. Nos. 4,828632, 4,878,967 and 4,879,095 to Adam et al. discuss rapidly solidified aluminum base alloy powder products of Al-Fe-Si-X where X is specifically vanadium or at least one element from the group V,Mn,Cr,Mo,W,Ta or Nb. However, Al-Fe-Si alloys containing W,Ta or Nb have not been discussed with extent to examples within these patents. Thus a full detailed and specified range of compositions and processes for consolidated articles from such powders has limited their usefulness.
This invention demonstrates the extent of the W,Ta and/or Nb addition to Al-Fe-Si base alloys and thus provides a set of engineeringly useful mechanical properties at ambient and elevated temperatures for these alloy systems.